Light Emitting Device Passivation and Reflective Layer Design
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Solution Overview
Problem
Light emitting devices face issues with reduced light intensity due to light absorption by solder pastes and branched electrodes, which also compromise the electrical contact area and reliability.
Innovation Solution
A light emitting device structure incorporating a passivation layer and insulating reflective layers to minimize light absorption, along with a transparent electrode and wetting layers to enhance electrical connectivity and light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder paste is used to mount the light emitting device chip, then electrical connection is achieved, but light intensity is reduced due to light absorption by the solder paste
Solution Approach 1:
The patent removes the solder paste from the light emission path by using a flip-chip mounting configuration where the light emitting surface faces upward and the solder connections are made only to the rear electrodes. This extracts the harmful light-absorbing material from the optical path while maintaining electrical connectivity through the substrate.
Solution Approach 2:
The patent introduces a reflective layer as an intermediary between the light emitting structure and the solder paste. This reflective layer redirects light that would otherwise be absorbed by the solder paste back toward the light extraction surface, thereby maintaining electrical connection while preserving light intensity.
2Reliability
If branch electrodes are used for current diffusion, then electrical connectivity is improved, but light efficiency deteriorates due to light absorption by the electrodes
Solution Approach 1:
The patent extracts the branch electrodes from the light emission path by positioning them on the rear surface of the device. The current diffusion function is maintained through the substrate while the light extraction path remains clear of light-absorbing metallic structures.
Solution Approach 2:
The patent applies different functional properties to different regions: the rear surface contains the electrical connection structures (electrodes and solder pads) optimized for electrical connectivity, while the front light emitting surface is optimized for light extraction with minimal metallic interference. This spatial separation of functions resolves the contradiction between electrical connectivity and light efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves light intensity by reducing absorption, secures electrical contact areas, and enhances light efficiency and reliability by optimizing the arrangement of reflective and wetting layers.
Implementation Method 1
an insulating reflective layer disposed on the passivation layer
Data Source
AI summary
The embodiments of the present invention relate to a light emitting device, a method for manufacturing a light emitting device, a light emitting device package, and a lighting device. A light emitting device according to an embodiment has: a light emitting structure including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer; a passivation layer disposed on the light emitting structure; and an insulating reflective layer disposed on the passivation layer. The passivation layer may include a first region disposed on an upper surface of the light emitting structure, and a second region disposed on side surfaces of the first conductivity type semiconductor layer, the second conductivity type semiconductor layer, and the active layer. The insulating reflective layer may be disposed on the first region, and an end portion of the insulating reflective layer may be disposed apart from an end portion of the first region.